1. Field of the Invention
The present invention relates to a device, and to a method of making the device, for dispensing a volatile substance into the environment. In particular, this invention relates to a device and a method of making it in a decorative form that nevertheless is effective to confine the volatile substance and to prevent undesirable dispensing of it in its liquid phase.
Many consumer products such as room deodorizers, insecticides, germicides, fragrances, and the like are volatile and may be released into an area, such as a room, to be treated merely by being exposed therein. Devices for dispensing these products are also available in many forms such as liquid and wick systems, blotter systems, and gel-type systems. However, the volatile substances may be subject to spilling, oozing, or waste in each of these systems. Therefore, various attempts have been made to provide improved devices for dispensing a volatile substance in a controlled manner so that the product is dispensed only in vapor form and undesirable spilling, oozing or waste of the product is avoided.
2. Description of the Prior Art
Various devices and methods for containing a volatile substance and for controlling the release of vapor from the substance are presently known. U.S. Pat. No. 4,158,440 (Sullivan et al), assigned to the assignee of the present invention, discloses a device for releasing a volatile substance that includes a reservoir of substance-absorbent material incapsulated in an envelope, at least a portion of which comprises a permeable material having a porosity at least equal to ultramicroporosity. The permeable envelope portion has a greater affinity for the substance than does the reservoir material. The remainder of the envelope comprises a material impermeable to the substance. Accordingly, the substance permeates through the permeable envelope portion to be released in vapor form into the environment.
U.S. Pat. No. 4,094,199 (Sullivan), also assigned to the assignee of the present invention, discloses a method of making a device for dispensing a volatile substance such as that disclosed in U.S. Pat. No. 4,158,440. This method includes the step of advancing a backing material, a reservoir material and a third material that is permeable to the volatile substance from respective supplies into close proximity to each other, with the reservoir material lying between the backing and permeable materials. The volatile substance is then supplied to the reservoir material to be held thereby. The three materials are fused together in a pattern defining a closed periphery or boundary to seal the reservoir material between the backing and permeable materials at the periphery.
In the method disclosed in the Sullivan et al patent, the fusing step may be performed by an ultrasonic welding apparatus or horn or a heat welding device. It has been learned that it is difficult to reliably form a homogenious seal about a non-circular fused boundary having three or more corners with such apparatus and particularly ultrasonic welding apparatus. It is believed that it is difficult to produce uniform ultrasonic energy about the periphery of a non-circular welding horn. Therefore, it is difficult to concentrate sufficient ultrasonic energy at the corners of a non-circular periphery to form a homogeneous fused seal about the boundary of a dispensing device so produced as is desired. However, homogeneous circular fused boundaries may be reliably made with a circular ultrasonic welding horn because ultrasonic energy may be uniformly distributed about the horn. Therefore, it is preferred that devices made using the method of the Sullivan et al patent have circular shapes. Nevertheless, for aesthetic reasons, it is often desirable to form a dispensing device having a shape other than a circular shape.
Still other devices for releasing a volatile substance are disclosed in U.S. Pat. Nos. 3,216,882 (Feldt et al.); 3,770,199 (Hoek et al.); 4,035,451 (Tringali); 2,988,284 (Smith); 3,685,734 (Paciorek et al) and 3,846,404 (Nichols). Other methods and apparatus for making envelopes which are filled with various substances are disclosed in U.S. Pat. Nos. 2,616,232 (Meyer); 2,970,141 (Rohdin); 3,007,848 (Stroop); 3,069,273 (Wayne); 3,495,992 (De For) and 3,978,636 (Clancy).